As a protocol by which a control device controls a switch for transferring a packet, there is known OpenFlow. OpenFlow is defined in Non Patent Literature 1.
In OpenFlow, the control device sets a flow entry to the switch. The switch processes the received packet according to the flow entry. The flow entry is information which defines how the packet is to be processed (for example, transfer, disposal, etc.). The flow entry is set for each flow of the packet. When the switch receives the packet and in the case of the presence of a flow entry corresponding to the flow of the packet, the switch processes the packet according to the flow entry. On the other hand, in the case of the absence of the flow entry corresponding to the flow of the received packet, the switch notifies the control device accordingly. The control device decides the flow entry corresponding to the flow of the packet and sets the flow entry to the switch.
In OpenFlow, as examples of messages transmitted or received between the control device and the switch, there are “Packet_in,” “Flow_mod,” “Packet_out,” “Flow_removed,” “stats_request,” “stats_reply,” and the like.
“Packet_in” is a message transmitted from the switch to the control device. “Packet_in” is used to transmit a packet not having a corresponding flow entry from the switch to the control device.
“Flow_mod” is a message transmitted from the control device to the switch. “Flow_mod” is a message for use in performing addition, change, or deletion of the flow entry by the control device to the switch.
“Packet_out” is a message transmitted from the control device to the switch. “Packet_out” is a message of giving an instruction for outputting a packet from a port.
“Flow_removed” is a message transmitted from the switch to the control device. “Flow_removed” is a message for notifying the control device of a fact that the flow entry is not used for a certain time period and is deleted from the switch due to timeout in such a case. When transmitting the “Flow_removed,” the switch also transmits the statistical information of a flow corresponding to the deleted flow entry to the control device.
“stats_request” is a message transmitted from the control device to the switch. “stats_request” is a message for requesting the switch to send the statistical information of the flow.
“stats_reply” is a message transmitted from the switch to the control device. “stats_reply” is used to transmit the statistical information of the flow, as a response to “stats_request,” from the switch to the control device.
Further, Patent Literature 1 describes a system for measuring application-categorized traffic volume information.
Moreover, Patent Literature 2 describes a wireless communication device for connecting to a plurality of wireless communication networks.